The present invention relates to a device for centering spectacle lenses and for fastening a holding part on the lenses; the device includes a mounting base, a guide or column sleeve arranged vertically thereon, as well as a height adjustable or displaceable and rotatable casing with which a swivel arm, which supports the holding part, is connected.
German Gebrauchsmuster No. 80 31 865.6, for example, discloses a device for centering spectacle lenses and for fastening a holding part on the lenses with a support which carries the lens, and a height adjustable and swingable supporting arm for the holding part, such as a block or suction apparatus which is to be mounted thereto. The supporting arm is subject to the force of a spring which presses or pulls the arm into its upper or lower end positions. A central guide or column sleeve is used around which the supporting arm is swivel mounted.
With the known devices, the swivel-mounted arm cannot be lowered exactly vertically onto the lens, since the swivel-mounted and height adjustable casing or bushing, which supports the arm, is guided on the column sleeve with play in the direction of rotation, i.e. in the circumferential direction of the casing. However, because of the transmission ratio of the distance between the holding part on the swivel arm and the column sleeve, each angular deflection of the arm allows errors to arise in the placement of the holding part on the lens, on the one hand regarding the distance or spacing of the guide part of the swivel arm, and on the other hand regarding the column sleeve.
It is therefore an object of the present invention to eliminate this disadvantage and, with simple means and without great structural expense and without taking a lot of time and effort, to be able to lower the holding part precisely vertically along a prescribed straight line onto the spectacle lens, so that the holding part maintains a desired precise position on the spectacle lens, and with the aid of which the lens can be inserted in an edge grinding machine, where the peripheral and bevel grinding is effected on the periphery of the lens.
It is a further object of the present invention to effect the play-free lowering of the casing, which is provided with the supporting arm, with a motor having an adjustable power.